Lighting a cigarette may not be a good way to relax and it may increase sensitivity to social stress, according to a new study by the French National Centre for Scientific Research published on Tuesday. Researchers found that exposure to nicotine, rather than withdrawal from it, which is commonly seen as anxiety-inducing in smokers, produced a stressing effect on lab mice, reports Efe news. “(The experiments) suggest that nicotine could enhance the effects of stress,” said Philippe Faure, the centre’s head of research, during the study’s presentation in Paris. Scientists from the University of Paris-Seine’s Neuroscience Laboratory and the University of Nice Sophia Antipolis’ Institute of Molecular and Cellular Pharmacology evaluated the levels of social stress in the rodents when exposed to nicotine. Social stress was induced when the critters were subjected to repeated aggressions by their dominant congeners. The nicotine receptors of some of the specimens were blocked, while others had their receptors activated. By studying their behaviour and the electrophysiological parameters of their brains, the centre’s experts found no signs of social stress when the receptors were blocked. The opposite occurred in mice with activated nicotine receptors, which showed signs of increased social stress. “Researchers have also been able to confirm that a mouse subjected to a single act of aggression by one of its congeners showed signs of stress only if it had been previously exposed to nicotine,” the study said. Although the research focused on mice, the centre said it would now study whether the results were translatable to human beings, as well as look into nicotine’s effects on other mood disorders.